1. Field of the Description
The present description relates, in general, to automultiscopic display methods and devices (e.g., methods and devices for creating differing views in differing directions without regard of eye position and without need for head-mounted gear to view a three-dimensional (3D) effect), and, more particularly, to multi-layer plenoptic displays that combine multiple emissive and light modulating planes that are adapted to provide increases in depth range and resolution when compared to both parallax barrier displays and volumetric displays.
2. Relevant Background
Displays that provide the illusion of three dimensions (3D) have become increasingly popular in many entertainment settings from movie theaters to venues such as amusement parks, shopping malls, and the like to home viewing with advances in televisions, computer monitors, and video game systems. The trend toward 3D display devices is likely to continue and is being driven in part by the increasing amount of 3D content available for movies, television, and video games.
While the majority of 3D displays currently require that the audience or viewers wear special glasses, there has recently been significant research toward autostereoscopic and automultiscopic displays. In automultiscopic display systems, techniques are used to display 3D images that can be viewed without the use of special headgear or glasses. It is generally agreed within the entertainment industry that automultiscopic displays unencumbered by glasses offer significant advantages over other 3D displays. Technological progress has been made in providing automultiscopic displays with improved resolution and user-perceived quality, and such progress may soon lead to more widespread adoption of automultiscopic displays as long as issues with occlusion and limitations on user viewing positions can also be addressed.
In general, parallax-based displays and volumetric displays are the two main types of 3D displays that currently are used to provide an automultiscopic experience. Parallax-based displays typically include a parallax barrier and employ horizontally modulated blocking patterns to provide different viewer rays for different viewing angles. A parallax barrier is a device that may be placed in front of an image source, such as a liquid crystal display (LCD) or the like, to allow the image source to show or display a stereoscopic or 3D image without the need for the viewer to wear 3D glasses. The parallax barrier may include a layer of material with a series of precision slits that allow each eye of a viewer to see a different set of pixels, and this creates a sense of depth through parallax in an effect that is similar to 3D images viewed with lenticular devices used with printed interlaced images. Volumetric displays provide images of 3D objects with correct focus and depth cues by creating a volume of individually controlled light sources, which is in contrast to the multiplexing of light rays for differing viewing directions done in parallax-based displays.
Unfortunately, both parallax-based and volumetric displays have disadvantages that have limited their use and more widespread adoption to display 3D content. Parallax-based displays typically require an extremely large display resolution to satisfy the depth range of most 3D scenes and to avoid aliasing artifacts. Further, the effective horizontal pixel count viewable by each eye is reduced by one half.
Volumetric displays typically operate by superimposing translucent light emitters, and, as a result, a key disadvantage with volumetric displays is that they cannot represent occlusion or view-dependent effects (e.g., a viewer can often see objects behind a displayed foreground image instead of the foreground image occluding or blocking the object from view). In conventional volumetric displays, all voxels that are occluded by other voxels in an input 3D model are merged such that there are no mechanisms to block the light and provide proper occlusion.
Some occlusion-capable displays have been designed that have been labeled volumetric by some in the industry. However, these displays are useful quite similar to parallax barrier-based displays. For example, instead of using blocking patterns to provide different viewing rays for different viewing angles, such displays may employ time multiplexing with a high-speed projector and a rotating vertical anisotropic mirror to attain the same effect. As a result of this design, such displays suffer from the same problem as the parallax barrier-based display in that their working volume is limited by the angular resolution, e.g., the number of images displayed during one revolution of the mirror. In addition, physically scaling the design poses significant mechanical challenges. Other “volumetric displays” attempting to provide a truer autostereoscopic display also have issues limiting their adoption. For example, one such system uses two volumetric displays and a set of beamsplitters to direct the light from each display to the correct eye, but this system only displays two fixed viewpoints.
Hence, there remains a need for improved 3D displays (or display systems) and automultiscopy display methods that can better handle occlusions and other issues limiting use of such displays such as limited number of viewers/viewpoints, specific and tight viewer positioning requirements, and aliasing artifacts.